Heavy duty linux server

I have a website that is getting decent traffic and ALSO performs
complicated computations (solving equations, rendering images etc).

Right now I have just one server, which does handle the load OK, most
of the time.

My question is about getting a second box. It would become the main
server, and the current one would become a hot backup. (with mysql
replication etc).

The main rationale is that I would suffer a bad embarrassment and bad
loss of business if my main server dies.

Here, my thinking is that I should get the baddest box possible, maybe
just a notch below that.

My spec so far is 8 GB of RAM, two dual core CPUs (to make four
cores), and four hard drives, to be arranged in some sort of RAID
arrangement. Maybe put three on RAID and use the fourth as backup/swap
disk.

My question is, will linux handle this many CPUs efficiently. Will 32
bit linux be able to use all 8 GB of RAM. I am aware that no process
could occupy more than 4gb, under 32 bit, which is fine with me.

The alternative is to get one less decent computer, and work harder on
having both share the load -- and on being able to turn any one of
them off.

I will appreciate some practical experiences here.

i

In comp.os.linux.networking Ignoramus7931 <(E-Mail Removed)> wrote:
> Will 32 bit linux be able to use all 8 GB of RAM. I am aware that no
> process could occupy more than 4gb, under 32 bit, which is fine with
> me.

Why limit yourself to a 32-bit linux kernel?

rick jones
--
oxymoron n, commuter in a gas-guzzling luxury SUV with an American flag
these opinions are mine, all mine; HP might not want them anyway...
feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...

On Fri, 9 Mar 2007 21:33:37 +0000 (UTC), Rick Jones <(E-Mail Removed)> wrote:
> In comp.os.linux.networking Ignoramus7931 <(E-Mail Removed)> wrote:
>> Will 32 bit linux be able to use all 8 GB of RAM. I am aware that no
>> process could occupy more than 4gb, under 32 bit, which is fine with
>> me.
>
> Why limit yourself to a 32-bit linux kernel?

How stable is 64 bit stuff?

Quite possibly, I will switch to 64 bit, I am just being conservative
here, not wanting to try out too new stuff for what makes money for
me.

i

Ignoramus7931 wrote:

> My question is, will linux handle this many CPUs efficiently. Will 32
> bit linux be able to use all 8 GB of RAM. I am aware that no process
> could occupy more than 4gb, under 32 bit, which is fine with me.

Yep -- my current desktop uses two Pentium III processors, and the desktop
I'm building now to replace it uses two dual core Xeons.

The standard Linux kernel doesn't support more than 4 GB of RAM, but there
is a compile-time option to allow (IIRC) up to 64 GB. Most distributions
ship with a pre-compiled kernel that has this option enabled, but it
probably won't be installed by default.

--
Toby A Inkster BSc (Hons) ARCS
Contact Me ~ http://tobyinkster.co.uk/contact
Geek of ~ HTML/SQL/Perl/PHP/Python*/Apache/Linux

* = I'm getting there!

Ignoramus7931 wrote:
> I have a website that is getting decent traffic and ALSO performs
> complicated computations (solving equations, rendering images etc).
>
> Right now I have just one server, which does handle the load OK, most
> of the time.
>
> My question is about getting a second box. It would become the main
> server, and the current one would become a hot backup. (with mysql
> replication etc).
>
> The main rationale is that I would suffer a bad embarrassment and bad
> loss of business if my main server dies.
>
> Here, my thinking is that I should get the baddest box possible, maybe
> just a notch below that.
>
> My spec so far is 8 GB of RAM, two dual core CPUs (to make four
> cores), and four hard drives, to be arranged in some sort of RAID
> arrangement. Maybe put three on RAID and use the fourth as backup/swap
> disk.
>
> My question is, will linux handle this many CPUs efficiently. Will 32
> bit linux be able to use all 8 GB of RAM. I am aware that no process
> could occupy more than 4gb, under 32 bit, which is fine with me.

I have a box with two hyperthreaded 3.06GHz Xeon processors and 8GBytes of
RAM. It is presently running Red Hat Enterprise Linux 3 ES (to be upgraded
to RHEL5 ES when it comes out). I am running the 2.4.21-47.0.1.ELhugemem
kernel, and the relevant part of the .config file for compiling the kernel is:

# CONFIG_NOHIGHMEM is not set
# CONFIG_HIGHMEM4G is not set
CONFIG_HIGHMEM64G=y
CONFIG_HIGHMEM=y
CONFIG_HIGHPTE=y
CONFIG_X86_PAE=y
CONFIG_HIGHIO=y
CONFIG_X86_4G=y
CONFIG_X86_SWITCH_PAGETABLES=y
CONFIG_X86_4G_VM_LAYOUT=y
CONFIG_X86_UACCESS_INDIRECT=y
CONFIG_X86_HIGH_ENTRY=y
# CONFIG_MATH_EMULATION is not set
CONFIG_MTRR=y
CONFIG_SMP=y
# CONFIG_NR_SIBLINGS_0 is not set
CONFIG_NR_SIBLINGS_2=y
CONFIG_SHARE_RUNQUEUE=y
CONFIG_MAX_NR_SIBLINGS=2
CONFIG_X86_CLUSTERED_APIC=y
CONFIG_X86_NUMA=y
# CONFIG_X86_NUMAQ is not set
CONFIG_X86_SUMMIT=y
CONFIG_X86_CLUSTERED_APIC=y
CONFIG_HAVE_DEC_LOCK=y

IIRC, the only thing I changed in here was
CONFIG_X86_4G=y
so that a single process can get the entire 4GBytes of virtual (and real)
memory space -- and the kernel can get one too if it wants to. You might not
need to do this and just run their normal hugemen kernel.
>
> The alternative is to get one less decent computer, and work harder on
> having both share the load -- and on being able to turn any one of
> them off.
>
> I will appreciate some practical experiences here.
>
> i


--
.~. Jean-David Beyer Registered Linux User 85642.
/V\ PGP-Key: 9A2FC99A Registered Machine 241939.
/( )\ Shrewsbury, New Jersey http://counter.li.org
^^-^^ 22:05:01 up 21 days, 10:29, 3 users, load average: 4.24, 4.30, 4.15

Ignoramus7931 wrote:

> How stable is 64 bit stuff?

Rock solid -- Linux has been doing 64-bit since before it was a twinkle in
Intel's eye -- it's supported Alpha and other such 64-bit platforms for
ages.

--
Toby A Inkster BSc (Hons) ARCS
Contact Me ~ http://tobyinkster.co.uk/contact
Geek of ~ HTML/SQL/Perl/PHP/Python*/Apache/Linux

* = I'm getting there!

On Sat, 10 Mar 2007 03:14:14 GMT, Jean-David Beyer <(E-Mail Removed)> wrote:
> Ignoramus7931 wrote:
>> I have a website that is getting decent traffic and ALSO performs
>> complicated computations (solving equations, rendering images etc).
>>
>> Right now I have just one server, which does handle the load OK, most
>> of the time.
>>
>> My question is about getting a second box. It would become the main
>> server, and the current one would become a hot backup. (with mysql
>> replication etc).
>>
>> The main rationale is that I would suffer a bad embarrassment and bad
>> loss of business if my main server dies.
>>
>> Here, my thinking is that I should get the baddest box possible, maybe
>> just a notch below that.
>>
>> My spec so far is 8 GB of RAM, two dual core CPUs (to make four
>> cores), and four hard drives, to be arranged in some sort of RAID
>> arrangement. Maybe put three on RAID and use the fourth as backup/swap
>> disk.
>>
>> My question is, will linux handle this many CPUs efficiently. Will 32
>> bit linux be able to use all 8 GB of RAM. I am aware that no process
>> could occupy more than 4gb, under 32 bit, which is fine with me.
>
> I have a box with two hyperthreaded 3.06GHz Xeon processors and 8GBytes of
> RAM. It is presently running Red Hat Enterprise Linux 3 ES (to be upgraded
> to RHEL5 ES when it comes out). I am running the 2.4.21-47.0.1.ELhugemem
> kernel, and the relevant part of the .config file for compiling the kernel is:

JD, just to clarify, if I was to switch to 64 bit linux, then there
are no special compile options to enable big RAM, right? I am
thinking, still, what linux to use for this, perhaps RHEL (CentOS)
would work for me.

i

> # CONFIG_NOHIGHMEM is not set
> # CONFIG_HIGHMEM4G is not set
> CONFIG_HIGHMEM64G=y
> CONFIG_HIGHMEM=y
> CONFIG_HIGHPTE=y
> CONFIG_X86_PAE=y
> CONFIG_HIGHIO=y
> CONFIG_X86_4G=y
> CONFIG_X86_SWITCH_PAGETABLES=y
> CONFIG_X86_4G_VM_LAYOUT=y
> CONFIG_X86_UACCESS_INDIRECT=y
> CONFIG_X86_HIGH_ENTRY=y
> # CONFIG_MATH_EMULATION is not set
> CONFIG_MTRR=y
> CONFIG_SMP=y
> # CONFIG_NR_SIBLINGS_0 is not set
> CONFIG_NR_SIBLINGS_2=y
> CONFIG_SHARE_RUNQUEUE=y
> CONFIG_MAX_NR_SIBLINGS=2
> CONFIG_X86_CLUSTERED_APIC=y
> CONFIG_X86_NUMA=y
> # CONFIG_X86_NUMAQ is not set
> CONFIG_X86_SUMMIT=y
> CONFIG_X86_CLUSTERED_APIC=y
> CONFIG_HAVE_DEC_LOCK=y
>
> IIRC, the only thing I changed in here was
> CONFIG_X86_4G=y
> so that a single process can get the entire 4GBytes of virtual (and real)
> memory space -- and the kernel can get one too if it wants to. You might not
> need to do this and just run their normal hugemen kernel.
>>
>> The alternative is to get one less decent computer, and work harder on
>> having both share the load -- and on being able to turn any one of
>> them off.
>>
>> I will appreciate some practical experiences here.
>>
>> i
>
>

On 3ÔÂ10ÈÕ, ÉÏÎç4ʱ39·Ö, Ignoramus7931 <ignoramus7....@NOSPAM.7931.invalid>
wrote:
> I have a website that is getting decent traffic and ALSO performs
> complicated computations (solving equations, rendering images etc).
>
> Right now I have just one server, which does handle the load OK, most
> of the time.
>
> My question is about getting a second box. It would become the main
> server, and the current one would become a hot backup. (with mysql
> replication etc).
>
> The main rationale is that I would suffer a bad embarrassment and bad
> loss of business if my main server dies.
>
> Here, my thinking is that I should get the baddest box possible, maybe
> just a notch below that.
>
> My spec so far is 8 GB of RAM, two dual core CPUs (to make four
> cores), and four hard drives, to be arranged in some sort of RAID
> arrangement. Maybe put three on RAID and use the fourth as backup/swap
> disk.
>
> My question is, will linux handle this many CPUs efficiently. Will 32
> bit linux be able to use all 8 GB of RAM. I am aware that no process
> could occupy more than 4gb, under 32 bit, which is fine with me.
>
> The alternative is to get one less decent computer, and work harder on
> having both share the load -- and on being able to turn any one of
> them off.
>
> I will appreciate some practical experiences here.
>
> i

Good!
http://fy4.net/ad.html

In <(E-Mail Removed)>,
Ignoramus7931 <(E-Mail Removed)> mentions:
>The alternative is to get one less decent computer, and work harder on
>having both share the load -- and on being able to turn any one of
>them off.

This might actually be your best plan. It's quite difficult though,
particularly where shared sessions are used and that sort of thing.

>I will appreciate some practical experiences here.

I've done the load balancing before. It's work, but it's worth it. Basically,
you need to think of everything as a /service/ as opposed to a /server/ with
each service having multiple hosts to handle it. The other thing to do,
is place front-end apache servers that pass given URL's off to machines
that are configured for that specific task.

For example, a mod_perl or java servlet engine might be expensive in terms
of resource consumption, a waste for serving a static image. So, you'd have
apache (or other web server) configured bare minimum, forwarding the URL's
off to machines that are better able to handle the content. (probably, it'd
handle static content right away but pass the rendering tasks to machines with
rendering, others to databases, etc..)

Configuration in this situation is a /nightmare/ you want some kind of directory
some place (I used LDAP when I did it) some place where you can keep all your
configs in one place.

When I did it, we had real machines...

These days, I would seriously consider getting a moderate heavy-weight box,
partitioning it into multiple virtual machines (UML, XEN, etc..) and then
adjusting the virtual machine(s) for the task. That way, you can basically copy
the whole machine, take it offline (or diagnose it, etc..) and put it back into
service. Adding new *physical* machines as they become needed, and you can do
easier testing.

If you do this, you can have fallbacks, which is *nice* but, it's a LOT of work,
something as simple as writing to a $!@% file suddenly become a major complex
operation.

Jamie
--
http://www.geniegate.com Custom web programming
Perl * Java * UNIX User Management Solutions

On Sat, 10 Mar 2007 23:31:06 +0000, Toby A Inkster wrote:

> Rock solid -- Linux has been doing 64-bit since before it was a twinkle in
> Intel's eye -- it's supported Alpha and other such 64-bit platforms for
> ages.


Just be aware that 3rd party support for 64 bit is often lacking. I don't
even know if Sybase has a version available, for example, and Oracle
claims to have one but I found numerous 32 bit dependencies.

I should have taken the hint when I learned that the installer of the 64
bit version was itself 32 bit. But I guess I'm slow <sigh>. And,
unfortunately, support was of very little help. They've apparently no
list of RPMs that are required in 32 bit, so their advise was "try until
something breaks".

Their API also has components (libraries) available only in 32 bit. That
would have cascaded to PHP, then Apache...

Fortunately, there's a second Oracle library that is available in 64 bit
form.

Anyway, before venturing into 64 bit land again (which I agree is
rock-solid on Linux itself) I'd double-check any third-party components I
needed for the machine.

- Andrew